21-01-2016, 11:03 AM
Latent Heat of Fusion
Kinetic-molecular theory
Heat & Internal Energy
Thermal Equilibrium
Temperature Scales
Laws of Thermodynamics
Entropy
Latent Heat of Vaporization
Specific Heat
Calorimetry
Heat Transfer Processes
Phase changes
Thermal Expansion
Heat Engines & Refrigerators
Kinetic-Molecular Theory
It was once common belief that heat was an invisible substance. It even had a name--“caloric,” and it was believed that it could be transferred between objects but neither created nor destroyed. To heat up an object this caloric had to flow into it. This, they thought, explained why objects expanded when heated. But this theory could not explain, for example, how heat could emanate from a cold piece of wood once it is set on fire? Where did the caloric come from? If it had been in the wood in the first place, the wood should have been hot all along.The caloric theory was abandoned in the 19th century and replaced with the kinetic-molecular theory.This new theory stated that all matter is made up of atoms/molecules in constant motion.The faster they move, the hotter an object will be.
Internal Energy
Internal energy (also called thermal energy) is the energy an object or substance is due to the kinetic and potential energies associated with the random motions of all the particles that make it up. The kinetic energy is, of course, due to the motion of the particles. To understand the potential energy, imagine a solid in which all of its molecules are bound to its neighbors by springs. As the molecules vibrate, the springs are compressed and stretched. (Liquids and gases are not locked in a lattice structure like this.)